a
High-Speed, 5 V, 0.1 F
CMOS RS-232 Drivers/Receivers
ADM222/ADM232A/ADM242
FUNCTIONAL BLOCK DIAGRAM
FEATURES
200 kB/s Transmission Rate
Small (0.1 F) Charge Pump Capacitors
Single 5 V Power Supply
Meets All EIA-232-E and V.28 Specifications
Two Drivers and Two Receivers
On-Board DC-DC Converters
؎9 V Output Swing with 5 V Supply
؎30 V Receiver Input Levels
Pin Compatible with MAX222/MAX232A/MAX242
5V INPUT
0.1F
C1+
0.1F
C1–
C2+
0.1F
VCC
+5V TO +10V
V+
VOLTAGE DOUBLER
+5V TO –10V
VOLTAGE INVERTER V–
0.1F
C2–
APPLICATIONS
Computers
Peripherals
Modems
Printers
Instruments
T1IN
TTL/CMOS
INPUTS*
T1
T1OUT
T2IN
T2
T2OUT
R1OUT
TTL/CMOS
OUTPUTS
R1
R2OUT
R2
R2IN
The ADM222, ADM232A, ADM242 are a family of high-speed
RS-232 line drivers/receivers offering transmission rates up to
200 kB/s. Operating from a single 5 V power supply, a highly
efficient on-chip charge pump using small (0.1 µF) external
capacitors allows RS-232 bipolar levels to be developed. Two
RS-232 drivers and two RS-232 receivers are provided on
each device.
The devices are fabricated on BiCMOS, an advanced mixed
technology process that combines low power CMOS with highspeed bipolar circuitry. This allows for transmission rates up to
200 kB/s, yet minimizes the quiescent power supply current to
under 5 mA.
The ADM232A is a pin-compatible, high-speed upgrade for the
AD232 and for the ADM232L. It is available in 16-lead DIP
and in both narrow and wide surface-mount (SOIC) packages.
The ADM222 contains an additional shutdown (SHDN) function that may be used to disable the device, thereby reducing the
supply current to 0.1 µA. During shutdown, all transmit/receive
RS-232
OUTPUTS
R1IN
ADM2xx
GENERAL DESCRIPTION
0.1F
EN
GND
SHDN
RS-232
INPUTS**
(ADM242)
(ADM222, ADM242)
* INTERNAL 400k⍀ PULL-UP RESISTOR
ON EACH TTL/CMOS INPUT
** INTERNAL 5k⍀ PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
functions are disabled. The ADM222 is available in 18-lead
DIP and in a wide surface-mount (SOIC) package.
The ADM242 combines both shutdown (SHDN) and enable
(EN) functions. The shutdown function reduces the supply
current to 0.1 mA. During shutdown, the transmitters are disabled but the receivers continue to operate normally. The
enable function allows the receiver outputs to be disabled
thereby facilitating sharing a common bus. The ADM242 is
available in 18-lead DIP and in a wide surface-mount (SOIC)
package.
REV. B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/461-3113
© Analog Devices, Inc., 2010
